Feature: Add power management to keep macOS client always responsive

macos/ScreenHandler.h

@@ -2,6 +2,7 @@
 
 #import <CoreGraphics/CoreGraphics.h>
 #import <dispatch/dispatch.h>
+#import <IOKit/pwr_mgt/IOPMLib.h>
 #import "../client/IOCPClient.h"
 #include <vector>
 #include <atomic>
@@ -132,4 +133,7 @@ private:
 
     // Input handler for mouse/keyboard control
     std::unique_ptr<InputHandler> m_inputHandler;
+
+    // Power management: prevent display sleep during remote desktop
+    IOPMAssertionID m_displayAssertionID;
 };

macos/ScreenHandler.mm

@@ -26,6 +26,7 @@ ScreenHandler::ScreenHandler(IOCPClient* client)
     , m_maxFPS(15)
     , m_qualityLevel(QUALITY_GOOD)  // Use fixed QUALITY_GOOD (H264) for web compatibility
     , m_h264Bitrate(3000000)  // 3 Mbps (matches Windows QUALITY_GOOD)
+    , m_displayAssertionID(0)
 {
     memset(&m_bmpHeader, 0, sizeof(m_bmpHeader));
 
@@ -115,6 +116,21 @@ void ScreenHandler::start(IOCPClient* client, uint64_t clientID)
     m_clientID = clientID;
     m_running = true;
 
+    // Prevent display sleep during remote desktop session
+    if (m_displayAssertionID == 0) {
+        IOReturn result = IOPMAssertionCreateWithName(
+            kIOPMAssertionTypeNoDisplaySleep,
+            kIOPMAssertionLevelOn,
+            CFSTR("SimpleRemoter - remote desktop session active"),
+            &m_displayAssertionID
+        );
+        if (result == kIOReturnSuccess) {
+            NSLog(@"Display sleep disabled for remote desktop (ID: %u)", m_displayAssertionID);
+        } else {
+            NSLog(@"Warning: Failed to prevent display sleep (error: 0x%x)", result);
+        }
+    }
+
     m_captureThread = std::thread(&ScreenHandler::captureLoop, this);
 }
 
@@ -130,6 +146,13 @@ void ScreenHandler::stop()
         m_h264Encoder->close();
         m_h264Encoder.reset();
     }
+
+    // Release display sleep assertion - allow screen to turn off
+    if (m_displayAssertionID != 0) {
+        IOPMAssertionRelease(m_displayAssertionID);
+        NSLog(@"Display sleep re-enabled (released ID: %u)", m_displayAssertionID);
+        m_displayAssertionID = 0;
+    }
 }
 
 void ScreenHandler::sendBitmapInfo()

macos/main.mm

@@ -6,6 +6,7 @@
 #import <signal.h>
 #import <unistd.h>
 #import <IOKit/IOKitLib.h>
+#import <IOKit/pwr_mgt/IOPMLib.h>
 #import <fstream>
 #import <thread>
 #import <atomic>
@@ -478,6 +479,30 @@ int main(int argc, const char* argv[])
     @autoreleasepool {
         NSLog(@"=== macOS Ghost Client ===");
 
+        // ============== Power Management: Keep System Awake ==============
+        // 1. Disable App Nap - prevent macOS from suspending this process
+        id<NSObject> powerActivity = [[NSProcessInfo processInfo]
+            beginActivityWithOptions:(NSActivityUserInitiated | NSActivityIdleSystemSleepDisabled)
+            reason:@"Remote control client must maintain persistent connection"];
+        NSLog(@"App Nap disabled, activity token acquired");
+
+        // 2. Prevent system idle sleep using IOKit power assertion
+        IOPMAssertionID sleepAssertionID = 0;
+        IOReturn result = IOPMAssertionCreateWithName(
+            kIOPMAssertionTypeNoIdleSleep,
+            kIOPMAssertionLevelOn,
+            CFSTR("SimpleRemoter macOS client - maintaining remote connection"),
+            &sleepAssertionID
+        );
+        if (result == kIOReturnSuccess) {
+            NSLog(@"Power assertion created: system idle sleep disabled (ID: %u)", sleepAssertionID);
+        } else {
+            NSLog(@"Warning: Failed to create power assertion (error: 0x%x)", result);
+        }
+
+        // 3. Display sleep: managed by ScreenHandler - only prevents display sleep
+        //    when remote desktop is actively connected (saves power when idle)
+
         // Setup signal handlers
         setupSignals();
 
@@ -549,6 +574,15 @@ int main(int argc, const char* argv[])
         }
 
         NSLog(@"Shutting down...");
+
+        // Release power assertions
+        if (sleepAssertionID) {
+            IOPMAssertionRelease(sleepAssertionID);
+            NSLog(@"Released sleep assertion");
+        }
+        // Display assertion is managed by ScreenHandler (released in stop())
+        // powerActivity is automatically released when exiting @autoreleasepool
+        (void)powerActivity;  // Suppress unused variable warning
     }
 
     return 0;